The two-metre-tall Queensland skyscraper has never started a professional game at number six, and only experienced 30 minutes there against the USA in the 2011 World Cup.

Even Simmons was shocked that McKenzie would choose him for the role in his return from a knee injury.

But he is relishing the thought of getting his hands on the ball in attack far more than he does in the second-row, instead of being the man who does the less-appreciated hard graft of cleaning out at rucks and tackling in tight.

A rugby league junior, the 33-Test lineout specialist must surprise a few fans and critics alike.

"I enjoy running the ball," he said. "I don't get to do it a lot so I guess I have to prove it to my own team-mates first this weekend that I'm able to do it and do it well and go from that.

"Numbers in the gym and things like that show that I could do it but I still have to prove myself in that position.

"Playing second row, you are obviously part of the engine room there and it's quite draining, so (it's good) to be a bit looser and quicker around the field like most sixes are."

McKenzie surprised all and sundry when he overlooked Ben McCalman for the role after fearless flanker Scott Fardy (concussion), a revelation for his breakdown work, was ruled out.

Dave Dennis is a specialist number six for NSW while Liam Gill has also played there off the bench at Test level.

Gill believes his fellow Reds forward will step up as the Wallabies have chosen to bolster their lineout instead of the breakdown.

"He'll fit in well. He'll play hard like a second rower," he said.

"He's a skilful second-rower who is tied down in tight so I think he'll get the chance to show his real skills."